Stanzertal Power Plant, Detailed Design

Project objectives

Production of electricity

Project description

Stanzertal Hydropower GmbH constructed a diversion power plant between Flirsch and Stans, Tyrol, with a headrace tunnel of approximately 5.2 km as its core element. The bottleneck capacity is 13.5 MW. The main section was excavated using a tunnel boring machine (TBM), while some sections were constructed using conventional tunnelling methods. The pressure shaft and ventilation shaft were excavated using the Alimak raise climbing method. The geological conditions in the TBM section were partly fractured, requiring repeated reinforcement measures. For the underpass of the Gondebach Tunnel (motorway), a conventional tunnelling method was used instead of the planned pipe jacking to minimise potential geotechnical problems caused by boulders.

Project data

• Design flow QA: 12.0 m³/s
• Gross head: 141.2 m, net head at QA: 135.2 m
• Maximum performance: 13.5 MW
• Operational capacity without storage operation: 52.2 GWh
• Length of TBM section: 3,781 m

Services

Tender phase: assessment geological & geotechnical risks, during tender preparation for construction of power plant Stanzertal lot 3, execution phase: detailed design of access tunnels & waterways as well as landfill.